Preparation and Properties of High-Quality Melt Growth Gd123 Bulks With Low Void Density: Flexural Strength at 77 K

Abstract

Mechanical properties of melt growth GdBa 2 Cu 3 O x (Gd123) large single domain superconducting bulks with Ag 2 O of 10 wt% and Pt of 0.5 wt%; 30 mm in diameter and 15 mm in thickness with low void density were evaluated at 77 K through flexural tests of specimens cut from the bulks, and compared to those of a conventional Gd123 with voids.Gd123 bulks were prepared with a seeding and temperature gradient method; first melt processed in oxygen, then crystal growth in air; two-step regulated atmosphere heat treatment. We discuss mechanical properties; the flexural strength and Young's modulus at 77 K. The results show that the flexural strength of the Gd123 at 77 K with low void density is 20 30% larger than that of a Gd123 conventional bulk which includes voids.

Preparation and Mechanical Properties of Large Single Domain GdBaCuO Superconductor With Low Void Density

“…Fig. 1 shows a heat pattern example for melt processing of the Gd-123 sample [6]. Finally, the samples were annealed in pure oxygen atmosphere.…”

“…2 for the superconductors which we have fabricated was performed using x-ray diffraction (XRD) and scanning electron microscope (SEM) [5], [6]. and were estimated from the magnetization measurements, using a Superconducting Quantum Interference Device magnetometer (SQUID) [5], [6].…”

“…Gd-123 bulk superconductor, therefore, is expected for large-scale applications such as flywheels, magnetic bearings, and magnetic separation, etc. We have studied superconducting and mechanical properties of melt-textured bulks of Gd-123 system with low void density [5], [6].…”

“…Therefore, it is very important to study and improve the mechanical properties to achieve structural reliability for applications. In this study, we report process, superconducting and mechanical properties of an innovative and robust Gd-123/Ag superconductor with low void density, a densified High-Quality Melt Growth bulk [5], [6], fabricated with a seeding and temperature gradient method in oxygen at the melt stage then in air at the growth stage. We discuss the hardness, the surface roughness, and the flexural strength of the bulks, because the hardness and the flexural strength would provide us with measuring of mechanical strength.…”

Mechanical properties of Gd123 superconducting bulks at 77 K

“…It is seen that Ag is distributed in the Gd123. For voids of the standard bulks, the average size is 91 µm for as-grown bulk [12] and 88 µm for annealed bulk [12], and the average area ratios are 15% and 14%, respectively. The void density of the densified bulk is almost zero, less than 1%.…”